Lean Condition: Will Data Logging Help???

[dsmith26]

Hey Guys,

I'm not a tuner (obviously from the title) as I strongly feel like the life of my car should be in the hands of a professional.

The other day I was giving someone a ride and did a hard pull and she performed as expected however on the second pull (couldn't stop while i was ahead) it seemed way down on power so I let out. I got home and pulled the plugs and it seems to be running lean. So I'm thinking either a fuel pump took a crap or my BAP quit working. Will I be able to determine which of these is causing my lean condition with data logging?? I've never data logged so I'm clueless in this department. If so, can you tell me what parameters I should be looking at to determine the issue??

Thanks Fellas!

 

[01yellercobra]

Datalogging will be able to tell you what's going on. You can watch your fuel pressure, duty cycle, and voltage drop. It'll give you an idea what's going on. But it won't specically tell you what component it is. Once you have a better understanding as to what's happening you can start diagnosing.

Get yourself a wideband installed. They're worth the money.

 

[dsmith26]

Thank You!

So can I assume that if duty cycle is close to 100% and fuel pressure drops off, the BAP isn't working?? Conversely, could I assume a fuel pump is bad if the voltage doesn't drop but the fuel pressure does??

 

[01yellercobra]

If you're reading close to 100% I would disconnect the BAP and compare the readings. If they don't change then I would assume the BAP is bad. If you disconnect it and things get worse then I would assume the fuel pump is bad. I don't have any experience with the BAP, so that's just saying how I would try it.

 

[dsmith26]

OK, I'll try this. I remember the duty cycle was 68% max on the dyno with the BAP (100% at 4800rpm prior to BAP).

Thanks again for the help.

 

[20SVT03]

also watch fuel trims and O2 sensors

 

[01yellercobra]

also watch fuel trims and O2 sensors

Those won't show anything under WOT. Your fuel trim should show whatever the commanded AFR is. And the computer isn't reading the O2's at that point.

 

[mustangmike1]

Thank You!

So can I assume that if duty cycle is close to 100% and fuel pressure drops off, the BAP isn't working?? Conversely, could I assume a fuel pump is bad if the voltage doesn't drop but the fuel pressure does??

We had a similar problem and it ended up being a kinked rubber hose on the pprv delete. We used clamps on the kink when installing but over time it still kinked beside it. You should be able to get a rough idea by datalogging on what the problem is.